Injector having a high flow rate ratio



April 1961 L. c. B. PICHON 2,981,483

INJECTOR HAVING A HIGH FLOW RATE RATIO Filed Sept. 16, 1960 I /2 6 17 l 3 20 I? 22 an; M

,6 H J 2 l5 8 I 2,981,483 INJECTOR HAVING A HIGH FLOW RATE RATIO Louis 'C. B. Pi'chon, Viroflay, France, assignor to Nord Aviation Societe Nationale de Constructions Aeronautiques, Paris, France, a joint-stock company of France v Filed se tic, 1960, Set. no. 56,488 Claims priority, application France Feb. 26, 1960 3 Claims. (31. 239-464) The present invention relates to an injector of liquid of the variable-section type, wherein the ratio of the flow rates is high when compared with the ratio of the pressures. of the liquid to be injected.

Such injectors are particularly adapted to supply modern air propulsiondevices such as turbojets, ramjets, etc., capable of being used between wide altitude and functional limits. They are generally constructed-by varying thefiow rate of the fuelas a function of its injection pressure.

Previously known injectors of this kind are either of a type comprising movable parts, givingrise to mechanical friction, or of a membrane type. Neither of these types exhibits all of the features necessary; both with respect to accuracy, of flowand qualityof the spray achieved.

\ In injectors comprising movable parts, mechanical friction excludes the possibility of ensuring the ability to reproduce operational characteristics so that it is necessary toahave individual fiowregulating means associated therewith. The provision of such means is a heavy handicap when using several injectors whose individual flow rates must be identical (as is the case for turbojet chambers). It cannot be used for supplying ramjets in which the number of injectors is high.

In deformable-membrane injectors, the rotation of the liquid to be injected, necessary for obtaining a satisfac tory spray, is not imparted under good conditions due to the lamination of the liquid at the level of the membrane. Moreover, the angular distribution of the jet is not satisfactory as the membrane has a preferential direction of deformation which is a function of the direction of lamination of the metal.

The object of the present invention is to provide an injector having a high ratio of flow rates and wherein the aforesaid drawbacks are overcome.

The high flow rate ratio injector in accordance with the invention is of a type comprising an injector body with a constant section ejection orifice, a mobile arrangement being frictionlessly movable in the injector body to vary the cross sectional area of the inlet to said port, said mobile arrangement including a needle-valve having a frusto-conical extremity whose side wall has' controls the travel of the needle-valve as a function of needle-valve with the injector body.

In one preferred embodiment of the invention, the resilient capsule is an aneroid capsule and each of its two main faces bears a cup in which is housed a swivel, one

the pressure of the liquid tobe injected, and connects the j of these swivels being connected with the needle-valve,

Patented Apr. 25, 1961 ulating rod. The head of the regulating rod projects outwards from the body of the injector, thereby-enabling the needle-valve to be adjusted without dismantling the injector. This adjustment can accordingly be effected on the bench while the injector discharges liquid.

Further features and advantages of the invention, particularly its simplicity of construction, will become apparent from the following description of one preferred embodiment thereof, with reference to the accompanying drawing, the single figure of which illustrates it in section along its axis.

As can be seen in this figure, the injector is comprisedby an attachment block I screwed to the extremity of a fuel supplytube, an injector body 2 and a mobile arrangement. 1 i

The attachment block 1 comprises an inlet port 3 for liquid and a nut 4 for the regulating rod 5 of the mobile arrangement. This nut 4 is set into the block 1. It has side faces pierced by holes 6 whose inlets are protected by a filter 7. The said regulating rod is adapted to screw into said nut. I e

A needle-valve seating 8 and an ejector nozzle 9 are secured, such as by insetting, in the extremity of the body 2. The ejector nozzle 9 comprises a chamber 10 and an ejector orifice 1'1.

The attachment block 1 and the body 2 of the injector A joint-seal 12 ensures a tight capsule 14. i

- The needle-valve 13 is of the type comprising a cylindrical part and 'a'frustoconical part, and its side walls have helicoidal grooves 15 formed'therein. The outerof any kind between the mobile arrangement and the body of the injector.

The aneroid capsule 14 is cylindrical. It carries on its main faces cups 16 and 17, having respectively housed the other constituting one of the extremities of the regtherein a swivel 18, attached to the needle-valve 13, and a swivel 19 constituting one extremity of the regulating rod 5. Each of these swivels is held in its respective cup by a circlip 20.

One extremity of the regulating rod 5 projects outside the injector, and after adjustment of the needle-valve it is locked in position by means of a cotter-pin 21.

The operation of the high flow rate ratio injector, forming the subject-matter of the present invention, is as follows:

The liquid enters the injector through port 3, fiows through the holes 6 after having passed through the filter 7, enters the capsule chamber 22 and flows into the helicoidal grooves 15 of the needle-valve 13 where it is rotated before reaching the chamber 10 of the ejector nozzle 9.

-In this chamber 10, the rotation is accelerated due to the conical configuration of the ejector nozzle 9, and the liquid, after having flowed through the ejector orifice 11, is expelled to the outside of the injector where it atomizes.

The adjustment of the injector iscarried out in such a way that when the liquid is either under a pressure which can be arbitrarily selected, or not under pressure at all, the needle-valve remains seated in its seating In this position the cross-sectional area of the passage for the liquid is fixed by the difierence existing between the diameter of the top of the seating andthe diameter at the bottom of the helicoidal grooves 15. When the liquid pressure rises upstream of this section,thecapsule 14 compresses and lifts the needle-valve 13, thereby increas- 3 ing the cross-sectional area of the passage for the liquid between the seating and the needle-valve.

Mechanical friction in connection with the needle-valve 13, which is the only guided movable member, is nonexistent since this valve is self-centered by the dynamic action of the streams of fluid flowing in the helicoidal grooves, both in the cylindrical and in the conical parts. This self-centering action, which is moreover facilitated by the cylindrical shape of capsule 14, is thus achieved hydraulically without contact by mechanical parts.

I Finally, this self-centering is ensured due to the lack of mechanical stress on the needle-valve 13, the connection with other parts being quite free because of the presence of the two swivels 1-8 and 19 permitting an articulated interconnection.

Lastly, spraying is ensured under the most favourable conditions by maintaining the liquid in rotation in the region between the seating and the needle-valve, then by the reduced dimensions of the chamber of the ejector nozzle 9 thereby reducing losses due to hydraulic friction. I Moreover, the control device for varying the flow rate makes it possible to have a high value for the ratio of the cross-sections. The maximum cross-section is a function of the range of displacement of capsule 14 and also of the angle of the cone between the needle-valve 13 and its seating. By adroit selection betweenthese different variables it is possible to design injectors adapted to extremely varied levels of flow and pressure as well as their ratios.

his to be understood that the present invention has just been described and illustrated merely by way of explanation without any intention of limiting the same, and that various modifications of detail can be made therein without exceeding its scope.

I claim:

1'. Injector having a high flow rate ratio, comprising an attachment block provided with a port for the entry of fuel, said block being screwed to the extremity of a fuel supply tube, an injector body, said body being screwed on to said attachment block, a needle-valve seating and an ejector nozzle, said seating being in contact with said body and said nozzle, the unit comprising said seating and said nozzle being fixed with respect to said body, a nut with pierced side faces for the passage therethrough of fuel, said nut being attached to said block, a regulating rod, adapted to be screwed into said nut and whose head projects outside the injector, a needle-valve having a cylindrical portion and a frustoconical portion, the outer surface of said needle-valve comprising helicoidal grooves, said frustoconical portion being capable of coming to bear exactly onto said seating, whereas said cylindrical portion does not engage the body of the injector, a resilient member interposed between the regulating rod and the needle-valve, and secured by suitable means to said rod and to said needle-valve, said suitable means being of the type allowing a certain degree of freedom, the displacements of said needle-valve relative to its seating being automatically regulated by the pressure exerted by the fuel on said resilient member, and said needle-valve being applied against its seating for minimum feed.

2. Injector having a high flow rate ratio as defined in claim 1, wherein the resilient member is an aneroid capsule.

3. Injector having a high flow rate ratio as defined in claim 2, wherein the two main faces of the aneroid capsule each have attached thereto a cup in which is housed a swivel, one of these swivels being attached to the adjusting rod and the other to the needle-valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,791,468 Grotta May 7, 1957 FOREIGN PATENTS 7 1,104,313 France June 8, 1955 

